Aryliminodimagnesium Reagents. XIV. Reactions with Nitrobenzenes Having Electronegative ortho-Substituents. Effects of Reaction Conditions on Condensation, Replacement, and Substitution

Article abstract of DOI:10.1246/bcsj.61.3581

In reactions of ArN(MgBr)2 with o-MeO- and o-halo-substituted nitrobenzenes, types and yields of products were different from those in its reactions with m- and p-substituted substrates.Condensation (leading to unsymmetrical azoxy- and azobenzenes), o-substituent replacement, and nuclear substitution took place.Relative yields of products were greatly affected by substituents and reaction conditions. o-MeO and o-F favor replacement, while o-Cl, o-Br, and o-I favor substitution.Replacement and/or substitution predominate when small molar excess of reagent and low concentration are used, while condensation predominates when large molar excess of reagent and high concentration are used, which phenomenon is mechanistically discussed.